Traditional low dynamic range (LDR) image and video coding schemes utilize color spaces like YCbCr with one luminance and two chrominance channels and subsampling of the chrominance channels to exploit the fact that the human eye is less sensitive to chroma variations than to luminance variations.
For high dynamic range (HDR) video an adaptive LogLuv color space has been proposed in [1]. Here it is possible to subsample the u and v chrominance channels as well.
However, especially in HDR images and video, edges with every high contrast may occur, i.e. areas with very high luminance next to areas with very low luminance. At such edges, artifacts due to the chroma subsampling can become visible.
FIG. A shows a tone map HDR image after a chroma subsampling with filters according to [2] and upsampling with filters according to [3]. Color bleeding artifacts are clearly visible at portions highlighted with a rectangle and indicated in an enlarged manner beside the image, namely at the rim of the flower pot and between the blades of the blind. These artifacts basically occur because chroma values from dark and bright regions get mixed-up during the process of chroma subsampling and upsampling.